Poor starting 350i
Discussion
Hi Everyone,
I wonder if you could help me with a starting problem I’ve been experiencing with my 350i. It began about 18 months ago when I noticed the car no longer fired up instantly from cold. It used to only take a couple of seconds to fire, but suddenly on occasion it was taking about 10 seconds instead, and at times needed a couple of tries before eventually firing. It only ever seemed to do this from cold, with ambient temperature not seeming to have any affect.
Just lately, the problem got a bit worse. It was now taking ages to start the car from cold every time, perhaps 20 seconds of cranking although hot starting was fine. Yesterday though, the car finally refused to start despite many minutes of cranking.
I had previously carried out lots of diagnostics to try and remedy the problem, but it was difficult since you only got about 10 seconds or so of cranking before the car eventually started, which didn’t give a lot of time for testing things. I did run through the various topics in the “Wedge Epistles” though to try and troubleshoot, including the EFI checking guide where by I checked all the pins on the ECU and tested all the sensors etc. Everything seemed to be fine.
Today, I have checked the following.
Fuel pressure was 2.5 bar on cranking.
Swapped the rotor arm, ignition module and coil with either brand new or known working spares.
Checked for any lose wires in the engine bay and reseated all the push fit electronical connectors.
The ECU tempterature sensor was also swapped last year as part of the troubleshooting.
On cranking, the car would try to fire, but not catch. The engine would shudder like it was about to start and the exhaust would emit a brief rumble, but the cranking would just continue for ages and ages. It probably spent about 15 minutes being cranked during the morning whilst I was checking things one by one, but it just wouldn’t catch.
Eventually, it finally spluttered into life with lots of grey/black smoke, but instantly cut out. I restarted it, and it cut out again instantly. After a few more tries, it ran roughly for about 10 seconds before settling down into a completely normal tickover. It revved freely and whilst I didn’t drive it, I’m sure it would have run faultlessly like it has done over the last 18 months.
So what could be causing the poor starting on a car that otherwise runs perfectly?
I’m certain that tomorrow morning it will have the same fault again, so is there something that happens during cranking that could account for this? I'm handy with a multimetre btw!
Also, most of the service parts are relatively new and of good quality (genuine Lucas arm and cap from RPI, good leads, coil etc etc). Flapper type AFM.
Thanks in advance,
Dan.
I wonder if you could help me with a starting problem I’ve been experiencing with my 350i. It began about 18 months ago when I noticed the car no longer fired up instantly from cold. It used to only take a couple of seconds to fire, but suddenly on occasion it was taking about 10 seconds instead, and at times needed a couple of tries before eventually firing. It only ever seemed to do this from cold, with ambient temperature not seeming to have any affect.
Just lately, the problem got a bit worse. It was now taking ages to start the car from cold every time, perhaps 20 seconds of cranking although hot starting was fine. Yesterday though, the car finally refused to start despite many minutes of cranking.
I had previously carried out lots of diagnostics to try and remedy the problem, but it was difficult since you only got about 10 seconds or so of cranking before the car eventually started, which didn’t give a lot of time for testing things. I did run through the various topics in the “Wedge Epistles” though to try and troubleshoot, including the EFI checking guide where by I checked all the pins on the ECU and tested all the sensors etc. Everything seemed to be fine.
Today, I have checked the following.
Fuel pressure was 2.5 bar on cranking.
Swapped the rotor arm, ignition module and coil with either brand new or known working spares.
Checked for any lose wires in the engine bay and reseated all the push fit electronical connectors.
The ECU tempterature sensor was also swapped last year as part of the troubleshooting.
On cranking, the car would try to fire, but not catch. The engine would shudder like it was about to start and the exhaust would emit a brief rumble, but the cranking would just continue for ages and ages. It probably spent about 15 minutes being cranked during the morning whilst I was checking things one by one, but it just wouldn’t catch.
Eventually, it finally spluttered into life with lots of grey/black smoke, but instantly cut out. I restarted it, and it cut out again instantly. After a few more tries, it ran roughly for about 10 seconds before settling down into a completely normal tickover. It revved freely and whilst I didn’t drive it, I’m sure it would have run faultlessly like it has done over the last 18 months.
So what could be causing the poor starting on a car that otherwise runs perfectly?
I’m certain that tomorrow morning it will have the same fault again, so is there something that happens during cranking that could account for this? I'm handy with a multimetre btw!
Also, most of the service parts are relatively new and of good quality (genuine Lucas arm and cap from RPI, good leads, coil etc etc). Flapper type AFM.
Thanks in advance,
Dan.
Thank you sooo much for the responses - so much to think about. As a result, I've had a theory but I'll answer the questions first :-)
Danny:-
I've had the cold start connected disconnected for a number of years now and found it made no difference to starting up until I encounted this hopefully unrelated problem. I forgot to mention that I tried refitting it this morning to see if it made any difference, but it didn't. Whilst cranking, the car didn't seem to smell as if it was flooded, but I can't be sure.
I tried it with various degrees of throttle, but it really didn't seem to make any difference whether it was depressed, pumped, poked or left alone... In the past, the car would always start on the button with no throttle pressing, as it does when it is warm in fact.
I haven't checked the plugs yet, so couldn't tell you if they are wet or not. As I had normal fuel pressure, I would guess they are. They are quite new, probably fitted about 10,000 miles ago and I would have given them a wire brush and set the gap at some point last year.
The coil has probably done about 10,000 miles too and was the recommened one for a Rover SDI. I must admit, I have no idea if it has a ballast resister or not. Is this an external attachment? The coil fitted is the same one that was used when the car had no starting issues, and the spare I tried today is the one that came with the car when I bought it direct from TVR Eng in 1997. I have white wires connected to the - and + terminals, so should one of these supply extra voltage when cranking? Can I measure this with a multimetre?
Ben420:-
Strangely enough, one of the things I am going to do in the next week or so is rebuild the whole plenum assembly as I’ve always been worried about air leaks around this area since I rebuilt it about 6 years ago. I once took the plenum off and found one of the trumpets laying lose, with another only holding on by a thread. When I reassembled, I don’t think I used enough sealing stuff so have always worried about it. I did start to suspect an air leak was the cause of the starting issues, although the car runs just great when warm.
I’ll report back when I’ve taken it all apart!
Al 350i:-
Very interesting that you mention about the car almost starting when you let go of the key, because mine does the same thing. I tried short sharp bursts of cranking and it seemed that it was going to catch every time. I could crank the engine for ages with that “almost catching” sound, but as soon as I let go of the key it seemed to want to start!
My current theory is that I may have a grounding issue somewhere. For about the same amount of time that I’ve had these starting issues, I’ve also had my wipers gradually losing power to the point you can only use them on full speed, and the driver’s window won’t close without a helping hand. I put this down to mechanical wear and it may be completely unrelated of course. The other thing I have noticed lately is that when indicating the volt meter bounces around in time to the “ticks”. I just figured it was a bad connection etc.
Sooo, could a slowly corroding grounding point lead to bad starting? My theory is that whilst the starter is being operated and using lots of current, the rest of the electronics are being supplied a reduced voltage. I noticed that my volt meter was only reading about 9 or 10 volts by the end of my nightmare today, which I just put down to a drained battery.
Sooooo, when the starter is operating, is it likely that if there is a weak ground in the engine bay, the rest of the electronical parts could be deprived of voltage to the point that they no longer operate, or am I being daft now? I assume a warm engine would be easier to start so the problem would be masked somewhat?
If I get chance I'll have a look tomorrow. Assume the main earthing point is the one just underneath the air filter, on the suspension strut? Does anyone know of any good tests I can do whilst trying to start the car from cold which would prove or disprove the theory? Maybe check the voltage of the + terminal of the coil?
Thank you in advance,
Dan.
Danny:-
I've had the cold start connected disconnected for a number of years now and found it made no difference to starting up until I encounted this hopefully unrelated problem. I forgot to mention that I tried refitting it this morning to see if it made any difference, but it didn't. Whilst cranking, the car didn't seem to smell as if it was flooded, but I can't be sure.
I tried it with various degrees of throttle, but it really didn't seem to make any difference whether it was depressed, pumped, poked or left alone... In the past, the car would always start on the button with no throttle pressing, as it does when it is warm in fact.
I haven't checked the plugs yet, so couldn't tell you if they are wet or not. As I had normal fuel pressure, I would guess they are. They are quite new, probably fitted about 10,000 miles ago and I would have given them a wire brush and set the gap at some point last year.
The coil has probably done about 10,000 miles too and was the recommened one for a Rover SDI. I must admit, I have no idea if it has a ballast resister or not. Is this an external attachment? The coil fitted is the same one that was used when the car had no starting issues, and the spare I tried today is the one that came with the car when I bought it direct from TVR Eng in 1997. I have white wires connected to the - and + terminals, so should one of these supply extra voltage when cranking? Can I measure this with a multimetre?
Ben420:-
Strangely enough, one of the things I am going to do in the next week or so is rebuild the whole plenum assembly as I’ve always been worried about air leaks around this area since I rebuilt it about 6 years ago. I once took the plenum off and found one of the trumpets laying lose, with another only holding on by a thread. When I reassembled, I don’t think I used enough sealing stuff so have always worried about it. I did start to suspect an air leak was the cause of the starting issues, although the car runs just great when warm.
I’ll report back when I’ve taken it all apart!
Al 350i:-
Very interesting that you mention about the car almost starting when you let go of the key, because mine does the same thing. I tried short sharp bursts of cranking and it seemed that it was going to catch every time. I could crank the engine for ages with that “almost catching” sound, but as soon as I let go of the key it seemed to want to start!
My current theory is that I may have a grounding issue somewhere. For about the same amount of time that I’ve had these starting issues, I’ve also had my wipers gradually losing power to the point you can only use them on full speed, and the driver’s window won’t close without a helping hand. I put this down to mechanical wear and it may be completely unrelated of course. The other thing I have noticed lately is that when indicating the volt meter bounces around in time to the “ticks”. I just figured it was a bad connection etc.
Sooo, could a slowly corroding grounding point lead to bad starting? My theory is that whilst the starter is being operated and using lots of current, the rest of the electronics are being supplied a reduced voltage. I noticed that my volt meter was only reading about 9 or 10 volts by the end of my nightmare today, which I just put down to a drained battery.
Sooooo, when the starter is operating, is it likely that if there is a weak ground in the engine bay, the rest of the electronical parts could be deprived of voltage to the point that they no longer operate, or am I being daft now? I assume a warm engine would be easier to start so the problem would be masked somewhat?
If I get chance I'll have a look tomorrow. Assume the main earthing point is the one just underneath the air filter, on the suspension strut? Does anyone know of any good tests I can do whilst trying to start the car from cold which would prove or disprove the theory? Maybe check the voltage of the + terminal of the coil?
Thank you in advance,
Dan.
Great news, well done.
Sorry I've not posted much recently - I have been reading this thread but due to being busy at work and the bad weather, I've not had chance to get the bonnet up.
I did however pop outside the other day and randomly tried to start the car. Started up instantly, which is frustrating as it makes troubleshooting difficult!
As soon as a half decent day comes along, I'll update this thread with my findings :-)
Dan.
Sorry I've not posted much recently - I have been reading this thread but due to being busy at work and the bad weather, I've not had chance to get the bonnet up.
I did however pop outside the other day and randomly tried to start the car. Started up instantly, which is frustrating as it makes troubleshooting difficult!
As soon as a half decent day comes along, I'll update this thread with my findings :-)
Dan.
Hi Everyone,
Finally an update and I think I've made some progress on my poor starting / running 350i. Yesterday I went through the troubleshooting section of the EFI document on the tvrwedgepages site and everything seemed to check out. I checked all the voltages / ohms on the circuits as described and they we're all healthy.
I then took the plenum off and discovered 3 of the trumpets were really lose in their holders, with one of them completely out. A further one had risen up about 1cm, so I took them all out and JB welded them in. Resealed the plenum, plus also removed the rocker covers, checked for obvious damage and resealed them too. I also checked all the breather hoses and am quite happy that everything is sealed.
I took the car for a test drive and it felts much better. Where as before the engine would routinely start to misfire / struggle at 4800rpm, this time it reved smoothly up to around 5400rpm. I repeated the test on a strip of abandoned road many times and have definitely gained another 600rpm of rev range. Previously, it was like the car had hit a wall at 4800rpm every time time, with lots if juddering, popping, banging etc.
However, I also noticed now that if you don't use wide open throttle, the car revs well past 6000rpm cleanly. 6200rpm was easy to achieve when driving at 4/5th throttle, but repeat with full throttle and the engine won't rev beyond 5500rpm. Whilst I don't normally drive at such high revs all the time, over the last 16 years the car has also done so if requested!
Soooo, any idea what could be causing this problem at full throttle? Maybe the vacuum mechanism on the distributor isn't working quite right, or could it be the fuel pressure regulator (standard, not rising rate) as I think this gets affected by inlet manifold vacuum too?
What else changes at wide open throttle compared to 4/5ths?
Thanks,
Dan.
Finally an update and I think I've made some progress on my poor starting / running 350i. Yesterday I went through the troubleshooting section of the EFI document on the tvrwedgepages site and everything seemed to check out. I checked all the voltages / ohms on the circuits as described and they we're all healthy.
I then took the plenum off and discovered 3 of the trumpets were really lose in their holders, with one of them completely out. A further one had risen up about 1cm, so I took them all out and JB welded them in. Resealed the plenum, plus also removed the rocker covers, checked for obvious damage and resealed them too. I also checked all the breather hoses and am quite happy that everything is sealed.
I took the car for a test drive and it felts much better. Where as before the engine would routinely start to misfire / struggle at 4800rpm, this time it reved smoothly up to around 5400rpm. I repeated the test on a strip of abandoned road many times and have definitely gained another 600rpm of rev range. Previously, it was like the car had hit a wall at 4800rpm every time time, with lots if juddering, popping, banging etc.
However, I also noticed now that if you don't use wide open throttle, the car revs well past 6000rpm cleanly. 6200rpm was easy to achieve when driving at 4/5th throttle, but repeat with full throttle and the engine won't rev beyond 5500rpm. Whilst I don't normally drive at such high revs all the time, over the last 16 years the car has also done so if requested!
Soooo, any idea what could be causing this problem at full throttle? Maybe the vacuum mechanism on the distributor isn't working quite right, or could it be the fuel pressure regulator (standard, not rising rate) as I think this gets affected by inlet manifold vacuum too?
What else changes at wide open throttle compared to 4/5ths?
Thanks,
Dan.
Thanks for the replies!
Just to answer. I haven't done a compression test for a couple of years, but when I did it was all quite healthy. Maybe time for a retest!
Oil pressure when hot is always around 2 bar when on the move and 1 bar when idle. Its been like that since I've owned he car, so assume its ok.
Haven't tried the "cold start" spray trick - should keep a can in the car maybe in case my starting issue returns.
Its quite possible that the distributor is at fault in all this. Whilst the timing hasn't been adjusted for years, it could be that the weights have become stuck or broken. I think a rebuild is something I should consider.
Going to the TVR event on the Isle of Wight this weekend so hopefully it will be kind to me until we get back.
Just to answer. I haven't done a compression test for a couple of years, but when I did it was all quite healthy. Maybe time for a retest!
Oil pressure when hot is always around 2 bar when on the move and 1 bar when idle. Its been like that since I've owned he car, so assume its ok.
Haven't tried the "cold start" spray trick - should keep a can in the car maybe in case my starting issue returns.
Its quite possible that the distributor is at fault in all this. Whilst the timing hasn't been adjusted for years, it could be that the weights have become stuck or broken. I think a rebuild is something I should consider.
Going to the TVR event on the Isle of Wight this weekend so hopefully it will be kind to me until we get back.
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